Importance of lateral lagoons for the ichthyofauna in a large tropical reservoir

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Acidentes do trabalho em pescadores artesanais da região do Médio Rio Araguaia, Tocantins, Brasil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Benthic macroinvertebrates in the Paranapanema reservoir cascade (southeast Brazil)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Controlling factors of benthic macroinvertebrates distribution in a small tropical pond, lateral to the Paranapanema River (São Paulo, Brazil).

The aim of the present study was to examine the benthic fauna in a marginal pond lateral to the Paranapanema River and to identify the main controlling factors of its distribution. Considering the small size of the lacustrine ecosystem, we expected that seasonal variations of the benthic community attributes are more important than spatial variations; Methods: Two samplings, one in March and another in August, were carried out at nine sites in the pond. Sediment samples were obtained through a Van Veen grab for invertebrate sorting, granulometric analysis, and for quantification of organic matter in sediment. Other abiotic factors were measured, such as water transparency, dissolved oxygen, pH, electric conductivity, temperature, and depth of sediment sampling sites. Regarding the comparative analysis at spatial scale, no significant variations in density of the benthic invertebrate community were found. Results: In relation to the studied abiotic factors, only depth presented significant differences among sampling sites; All the measured environmental parameters presented significant differences among sampling months, except depth and the physical and chemical characteristics of the sediment. The abundance of Chaoboridae and Chironomidae was the unique attribute with a significant difference in comparing the two months. A higher abundance of taxa occurred in August, especially for Oligochaeta, Nematoda, Chaoboridae, and Chironomidae; Conclusions: Because of the low structural complexity of the studied pond, we concluded that the changes in benthic macroinvertebrate community attributes were mainly due to seasonal effects.

Tafonomia de tempestitos conchíferos amalgamados da formação Teresina em Rio Preto (Estado do Paraná, permiano médio, bacia do Paraná) e suas implicações paleoambientais

The deposits of the Permian Teresina Formation are mainly characterized by fi ne-grained siliciclastic rocks and centimetric intercalations of tempestites (bioclastic sandstones and coquinas). Despite the relevance of the bivalve-rich carbonate beds of the Teresina Formation to paleoenvironmental studies, their taphonomy is still poorly studied. The fossil concentration studied in this work was found in a quarry in the city of Irati, Rio Preto district, Parana State. The fossil concentration is located in the middle/upper portion of the unit, far from the top. The studied bed is a bioclastic, intraclastic, peloidal, grainstone/ packstone, with abundant bivalve shell fragments, pelitic and micritic intraclasts, peloids, rare ooids and oncoids, as well as permineralized of Lycophyta microphylles and fish scales. The grains of this carbonate concentration show: high degree of time-averaging, variable degree of packing (dense to disperse), no sorting and chaotic orientation. Notably, the concentration includes a mixture of elements which are indicative of: a) restrictive, low energy, carbonate environment (peloids, ooids and oncoids); b) subaerial environment surrounding the main body of water (Lycophyta microphylles) and c) quiet-water environment punctuated by storm events, where the suspension-feeding bivalves thrived. At least four depositional events caused by storm fl ows were recorded. The amalgamated nature of the bed is a result of storm events in an intracratonic basin with very low seafl oor slope and low rates of sedimentation and subsidence.

Tafonomia de biválvios em calcários oolíticos da formação Teresina (Bacia do Paraná, Permiano Médio, Prudentópolis, PR)

Herein, it is presented the first detailed taphonomic study on bivalve mollusk shells preserved in the oolitic limestones of the Teresina Formation (probably Kungurian-Roadian, Lower-Middle Permian) in the eastern margin of the Parana basin. The selected beds are located in two quarries (informally named PRU 1 and PRU 2) in Prudentopolis municipality (Center-South Parana State), and positioned approximately in the middle of the formation and probably in the Pinzonella illusa Zone. The PRU 1 limestone ([approximately]30 cm thick), which is partially silicified and intercalated with predominantly pelitic rocks, is classified as a bivalve oolitic grainstone. The basal contact is erosive and the top shows symmetrical ripple marks, which are draped by shale with mud cracks. There are two fining-upwards successions characterized by dense to dispersed packing of the shells, which are usually disarticulated, randomly oriented (many nested/stacked) and mixed with some Formapelitic intraclasts. Microhummocky cross-stratification occurs a little below the top of the bed. The PRU2 bed is classified as ooidbivalve rudstone[approximately] (~5 cm thick), where all shells are disarticulated and fragmented, showing dense packing. The bivalves probably inhabited a muddy substrate and were mixed (as parautochtonous and allochthonous bioclasts) with ooids during high-energy storm events, including posterior shell displacement as a result of bioturbation. Thus, the calcareous beds represent amalgamated proximal tempestites with a complex taphonomic history, strong temporal/spatial mixing of bioclasts and limited paleoecological resolution. They are a typical example of shell beds generated in a huge epeiric sea, which was not necessarily connected to the ocean and where very low depositional-slope gradient, very slow subsidence and minimum sediment accommodation space caused frequent sediment reworking by storm related processes.

Occurrence of Pseudosida ramosa Daday, 1904 (Crustacea: Cladocera: Ctenopoda) in marginal lakes of the Paranapanema River, with comments on its distribution.

Aim: Contribute to the understanding of the distribution of a littoral cladoceran, Pseudosida ramosa Daday, 1904, in Brazil, with special reference for the Paranapanema River basin (Southeast Brazil); Methods: The specimens were sampled in two floodplain lakes located in the middle Paranapanema River basin, in the boundary of São Paulo and Parana States, using a standard plankton net (50 [mu]m mesh size). Trinocular microscopic with camera lucida and milimetric scale was used for the observation and measurements of the specimens; Results: Only three individuals were found (in winter and summer), despite of an extensive sampling program during 17 consecutive months of observations in both lakes. The largest body length was 1,146 [mu]m. The taxonomical identification followed Korovchinsky (1992); Conclusions: This species have a wide geographical distribution in Brazil, but it is restricted to zones colonized by aquatic macrophytes and seems to occur in low population abundance. The scarcity of registers of P. ramosa demonstrates the necessity of deeper investigations of littoral habits as well as the important role of this kind of environment for the conservation of the rivers/reservoirs biota, including some possible rare species.

Dinâmica inicial da composição florística de uma área restaurada na região do Pontal do Paranapanema, São Paulo, Brasil

O Pontal do Paranapanema, extremo oeste do Estado de São Paulo, é marcado pela recente devastação florestal, e ações visando à recuperação de áreas onde outrora havia cobertura florestal tornam-se indispensáveis para a conservação da biodiversidade na região, principalmente quando se trata de áreas de Reserva Legal ou Preservação Permanente. Diante do exposto, esta pesquisa teve como objetivo analisar a dinâmica inicial da composição florística em uma área de Reserva Legal restaurada. O trabalho foi realizado no assentamento Nova Esperança, Município de Euclides da Cunha Paulista, em uma área de 26,75 ha. O levantamento das espécies foi realizado pelo método de parcelas (16 parcelas de 20 x 30 m) em duas fases distintas do plantio, e as análises foram feitas utilizando-se o software Fitopac. Os resultados evidenciaram diminuição da biodiversidade pela alta mortalidade de espécies, levando à conclusão de que em projetos de restauração as intervenções são necessárias para a manutenção do plantio mesmo em sua fase inicial.

Fish community alterations due to pollution and damming in Tiete and Paranapanema rivers (Brazil)

The Tiete River crosses the metropolitan region of São Paulo (Brazil) and receives a large amount of pollution, in contrast to Paranapanema River which runs in a less populated area. In the inferior portions of the basins of these rivers, a series of reservoirs has been built for hydroelectric energy generation which improve the water quality due to the decantation of suspended soils and aeration in the water spills.Twenty-nine sampling sites were established along the two rivers and in each sampling site, two groups of eight gillnets were used with standardized sizes in two seasons: winter (dry season: June-September 1994) and summer (rainy season: December-March 1995). The fishes were measured and weighed.Twenty-five parameters related. to the water were recorded. PCA and cluster analysis helped to identify two groups of sampling sites. The first one corresponds to the rainy season samples, while the second corresponds to the dry season samples, so evidencing strong seasonal environmental variation. However, the dry season group is still divided into polluted and non-polluted sites, showing that during drought there are larger effects of pollutant concentration due to the decreased flow.A total of 415 kg of fish were caught, corresponding to 8324 individuals belonging to 64 different species, in 22 families and four orders of Teleostei. The largest catches occurred in the middle Tiete River. The catches in the reservoirs of the Tiete River, during the rainy season are superior to those of the dry season. on the other hand, sampling sites located in running water presented an inverse pattern with the largest catches in the dry-season. In river Paranapanema, catches are lower than in the Tiete River, except in Rosana Reservoir during the rainy season. Fish diversity was shown to be a good-indicator of environmental stress. In Tiete River an expressive fall in species richness was detected in the polluted stretches, with dominance of one or two species. In the intermediary stretches, the presence of rapids increases the amount of dissolved oxygen, allowing the development of the most abundant and diverse fish community of the river. Fish communities in the reservoirs of the inferior stretch of Tiete River are more diverse. on the other hand, the damming of the superior reaches of Paranapanema River provoked a decrease in diversity. 0 the whole, types of local fish communities detected, showing different compositions and specific abundances, revealed different ecological situations. A discriminant analysis revealed that the parameters of the water influencing the fish community were: dissolved oxygen, conductivity, nitrogen (nitrate, ammoniacal and albuminoid), phosphate, alkalinity, hardness and iron. Copyright (C) 2003 John Wiley Sons, Ltd.

A aproximação de campo médio de Bethe-Peierls

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Distribuição de mercúrio em diferentes solos da Bacia do médio Rio Negro-AM: influência da matéria orgânica no ciclo biogeoquímico do mercúrio

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A construção coletiva interdisciplinar em educação ambiental no ensino médio: a microbacia hidrográfica do Ribeirão dos Peixes como tema gerador

O Ribeirão dos Peixes é o principal corpo de água do município de Dois Córregos (SP), e as conseqüências das atividades antrópicas no local exigem urgentes providências para a recuperação do sistema. Considerando que as bacias hidrográficas representam uma temática bastante adequada para um programa de Educação Ambiental e, ainda, as dificuldades/necessidades apresentadas, pelos professores, para o desenvolvimento de práticas que estimulem a conscientização dos alunos com respeito às questões ambientais, o presente estudo visou à formação interdisciplinar de educadores que atuavam no terceiro ano do ensino médio de uma escola estadual, no sentido de possibilitar que trabalhassem posteriormente com seus alunos a dimensão ambiental da microbacia hidrográfica do Ribeirão dos Peixes. Uma investigação inicial sobre as práticas pedagógicas dos professores em relação à abordagem do tema e à Educação Ambiental forneceu subsídios para que este trabalho fosse conduzido, por meio da Pesquisa-ação-participativa e complementada pelo Ensino por pesquisa.

O discurso de alunos do ensino médio a respeito da camada de ozônio

O objetivo deste trabalho foi investigar os gêneros de discursos utilizados por alunos da terceira série do Ensino Médio a respeito de um dos conteúdos vinculados ao ensino de química ambiental: o estudo do gás ozônio e os problemas relacionados à degradação de sua camada na atmosfera terrestre. Os resultados apontam para um nível de envolvimento discursivo em que se percebe a apropriação da linguagem científica como ferramenta de argumentação acerca das questões ambientais.

A sistemática incompreensão da teoria quântica e as dificuldades dos professores na introdução da Física Moderna e Contemporânea no Ensino Médio

O objetivo desta pesquisa é avaliar a proposta de introdução da Física Moderna e Contemporânea no Nível Médio da Educação Básica. Parte-se do pressuposto de que os professores assumem, às vezes até subconscientemente, que a teoria base da FMC é incompreensível. Investigamos, em 2007, os discursos de cinco professores de Física de um município da região Nordeste, visando compreender as possibilidades desses professores introduzirem a FMC em suas aulas de Física e em que medida estas possibilidades estão associadas às suas formações profissionais. Para a construção e análises dos discursos pautamo-nos na Análise de Discurso Francesa e em referenciais da Teoria Crítica da Educação. Constatamos que apesar de atribuírem papel relevante à introdução da FMC no Nível Médio, os professores não estão encarando este desafio.

O conhecimento de polígonos e poliedros: uma análise do desempenho de alunos do ensino médio em exemplos e não-exemplos

O artigo pretende mostrar os resultados de uma pesquisa cujo objetivo foi analisar o desempenho de alunos do Ensino Médio na identificação de exemplos e não-exemplos de polígonos e poliedros, tendo em vista os atributos definidores e atributos irrelevantes. Participaram da pesquisa 253 alunos, distribuídos em três séries do Ensino Médio de uma escola pública, que responderam um teste de exemplos e não-exemplos. Posteriormente, foram selecionados seis alunos para serem entrevistados sobre seus conhecimentos a respeito dos exemplos e não-exemplos. Os resultados mostraram que os participantes obtiveram uma média baixa (M = 5,59) na tarefa que exigiu a identificação de exemplos e não-exemplos de polígonos e poliedros. A análise das entrevistas mostrou que a maioria dos alunos considerou que o atributo irrelevante dos polígonos analisados não interferiu na resposta. Contudo, evidencia-se, de modo geral, que esses alunos apresentaram um conhecimento conceitual longe do esperado para esse nível de ensino.